Some characteristics of the arc when welding steel type 18-8 with an oxidized surface

The arc parameters have been studied in welding plates of the steel 18-8 having clean and oxidized surfaces. An explanation is suggested of the arc compression mechanism during the arc pass from a clean to an oxidized metal surface. The arc behaviour has been investigated depending on the oxide film thickness. It has been found that, when passing from a clean to an oxidized surface, a spontaneous increase in voltage occurs and, respectively, a decrease in current of the arc; the arc efficiency grows. With a thin or a thick film thickness (as compared to the optimal one) the weld penetration depth decreases and the weld formation worsens. The measurements of the arc anodic spot depending on the anode material and on the type of the film at the anode surface have shown that the current-conducting anodic spot with the arc welding over an oxidized surface is 1.5 times as low as that over a clean surface. The extent of the arc compression is the more, the higher is the oxide film melting point and the stronger is the electric conductivity dependence on the temperature